PRELIMINARY DATA MOTIVATIONS Increased water demands & diminishing high quality water sources lead to the use of previously underutilized technologies METHODOLOGY CONCLUSIONS • The presence of calcium in solution negatively impacts the performance of ion exchange for both bicarbonate-form and chloride-form. The presence of magnesium also impacts performance. • Chloride-form ion exchange isn’t impacted as greatly by the presence of divalent cations as bicarbonate-form. • Bicarbonate-form anion exchange is greatly impacted by the presence of divalent cations. The presence of magnesium has the most profound and immediate impact. FUTURE WORK • Complete additional regeneration cycles and perform regeneration cycles on waters containing no cations, and waters containing Co 2+ . • Investigate the biological fouling of bicarbonate- form biological fouling • Innovative regeneration by CO 2 (g) sparging and optimization Figure 1: Preliminary results showing resin performance in absence of divalent cations. Synthetic water contained Santa Fe River NOM, nitrate, sulfate, bicarbonate, and chloride. Figure adapted from Rokicki and Boyer 2011 2 . Calcium Magnesium Figure 3: DOC removal by chloride-form ion exchange resins over multiple regeneration cycles in the presence of calcium. Figure 4: DOC removal by bicarbonate-form ion exchange resins over multiple regeneration cycles in the presence of calcium. Species pK sp 1 MgCO 3 5.17 CaCO 3 8.54 CoCO 3 12.84 Species mg/L meq/L Cl - 4.03 0.06895 HCO 3 - 5.79 0.06895 SRNOM 14 0.06895 X 2+ Varies 0.06895 Figure 5: DOC removal by chloride-form ion exchange resins over multiple regeneration cycles in the presence of magnesium. Figure 6: DOC removal by bicarbonate-form ion exchange resins over multiple regeneration cycles in the presence of magnesium. • Jar tests are run in triplicate • Regeneration occurs at 100x equivalence capacity of resin ACKNOWLEDGEMENTS The author would like to thank Dr. Treavor Boyer for all his support and guidance. I would also like to thank the Boyer research team for all their help and support in and out of the laboratory. References 1 Dean, J.A., 1999. Lange's Handbook of Chemistry, 15th ed. McGraw-Hill.. 2 Rokicki, C.A., Boyer, T.H., 2011. Bicarbonate-form anion exchange: Affinity, regeneration, and stoichiometry. Water Research 45, 1329 -1337. 3 Walker K.M., Boyer, T.H., 2011. Long-term performance of bicarbonate-form anion exchange: Removal of dissolved organic matter and bromide from the St. Johns River, FL, USA.. Water Research 45 (9), 2875-2886. RESULTS • Ion exchange (IEX) may be a treatment solution for certain waters with higher levels of natural organic matter (NOM): IEX Resin NOM NOM NOM NOM HCO 3 - HCO 3 - HCO 3 - HCO 3 - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - IEX Resin NOM NOM NOM NOM HCO 3 - HCO 3 - HCO 3 - HCO 3 - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - • However, brine associated with chloride- form resin limits the potential applications of IEX. Bicarbonate-form would generate easier to dispose of regenerant and would prevent increase of salinity of local waters. • It is unknown how the presence of bicarbonate within the resin structure will react with divalent cations: Table 2: Synthetic water composition Table 1: Carbonate mineral solubility products. Table adapted from Dean 1999 1 Kinetic study jar tests: Regeneration of resin: IEX Resin HCO 3 - HCO 3 - X 2+ X 2+ H + H + HCO 3 - Brine disposal is a major concern, much like RO concentrate, it often impedes the implementation of this technology. Impact of divalent cations on fouling potential of bicarbonate-form anion exchange resins Christopher A. Rokicki, and Treavor H. Boyer 1 Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 1 [email protected] ~ (352)846-3351 ~ http://www.ees.ufl.edu/homepp/boyer/ Figure 2: SEM images of chloride- and bicarbonate-form resin after 14 regenerations. Figure adapted from Walker and Boyer 2011 3 . 0.5ml/L IEX resin 1L DI & salt Mix 30min at 150 RPM Stop, allow to settle, decant Add 1L DI to wash, mix 10min Repeat twice 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% r0 r1 r2 r3 % DOC removal regeneration# M-Cl M-HCO3 0% 10% 20% 30% 40% 50% 0 50 100 % DOC removal time (min) r0 r1 r2 r3 chloride-form chloride-form 0% 10% 20% 30% 40% 50% 0 50 100 % DOC removal time (min) r0 r1 r2 r3 bicarbonate-form 0% 10% 20% 30% 40% 50% 0 50 100 % DOC removal time (min) r0 r1 r2 r3 bicarbonate-form 0% 10% 20% 30% 40% 50% 0 50 100 % DOC removal time (min) r0 r1 r2 r3 chloride-form